1. Field of the Invention
The present invention relates to a high definition television camera apparatus, and more particularly to a high definition television camera apparatus constituted of a high definition television image pickup unit and a television signal processing unit and being capable of outputting a high definition television video signal and a standard television video signal converted from the high definition television video signal and capable of correcting each video signal to have characteristics (e.g., gamma characteristics) specific to each of standard television system and high definition television system.
2. Description of the Related Art
A television camera (television camera apparatus) is generally constituted of main components including a camera head (image pickup unit) and a camera control unit (CCU). A television camera with the integrated camera head and camera control unit is used widely. The camera head has: an image pickup lens for condensing an image light of an object; an image pickup element for photoelectrically converting light incident from the image pickup lens into video signals; a pre-amplifier for amplifying a video signal supplied from the image pickup element to a predetermined signal level; a gamma correction circuit for correcting the video signal to have a gamma value specific to a television system; and a video signal processing circuit for subjecting the gamma corrected video signal to necessary processes, including a knee process, a white clip process, a white balance adjusting process, a black balance adjusting process, a masking process and the like, to thereafter output the processed video signal having a desired level which is then supplied via a cable to the camera control unit.
The camera control unit processes the video signal having a desired level sent from the camera head via the cable in predetermined manners, and outputs the processed video signal having a predetermined level to various apparatuses such as a video monitor and a video tape recorder. The camera control unit also receives a control signal supplied from, for example, a remote controller, and outputs a necessary control signal to the camera head via the cable to thereby remotely control the necessary characteristic values to be used during the processes by the camera head, the values including a gamma characteristic value, a white balance value and the like.
The above-described structures of the camera head and the camera control unit are fundamental to a general television camera, and applicable to both standard and high definition television cameras.
As well known, the above-described characteristic correction circuit for a video signal, e.g., the gamma correction circuit, is a circuit for inversely correcting non-linear characteristics of an image pickup element of a camera head, an image display tube of a video monitor, and the like, in accordance with a correction amount corresponding to a predetermined gamma correction curve, so as to linearize the luminance transmission characteristics of the whole television system: from the television camera or camera head for picking up an image of an object and generating a video signal of the object image; to the video monitor for reproducing the object image from an input video signal.
For general gamma correction by a standard television video camera apparatus, a gamma value capable of properly correcting a video signal output from a television camera or camera head is usually set to 0.45 (an inverse of 2.2), assuming that the gamma value representative of a degree of a gamma correction curve used for linearizing non-linear characteristics of an image pickup element is about 1.0 (this gamma value is hereinafter called a gamma value of an image pickup element, where applicable) and the gamma value of a standard television display tube is about 2.2.
However, there are differences of many characteristics such as a gamma value and a luminance signal (Y) matrix of a video monitor, between a high definition television video signal monitor and a standard television video signal monitor. Therefore in many cases a proper gamma value for processing a video signal of a high definition television camera is different from that for processing a video signal of a standard television camera.
As described above, similar to a standard television camera, a high definition television camera also has a gamma correction circuit for correcting a gamma value for a high definition television video signal and outputting a gamma-corrected high definition television video signal matching a high definition television system. There is an apparatus, for example, a high definition television camera apparatus, which has a built-in television camera signal conversion circuit for converting a high definition television video signal output into a standard television video signal output. In such a high definition television camera apparatus, the television camera signal conversion circuit converts a high definition television video signal output supplied from the high definition television image pickup unit (camera head), with its gamma value having been corrected so as to match a high definition television system, into a standard television video signal output, without changing the gamma value. Therefore, the gamma value used for the gamma correction of the high definition television video signal is always the same as that used for the gamma correction of the standard television video signal output.
As above, in a high definition television camera apparatus constituted of a high definition television image pickup unit (camera head) and a television signal conversion circuit for converting a high definition television video signal output into a standard television video signal output, the same characteristic values such as a gamma value or other values not changed between the high definition and standard television systems are used.
Of various characteristics for a television video signal, proper values of the characteristics such as white balance and the like are generally the same. Therefore, even if the same characteristic values are used for both the high definition and standard television video signals, no practical problem occurs.
However, substantially different proper values of the characteristics such as black balance, gamma value, detail (contour), and masking are used for both the standard and high definition television video signals. Therefore, even if each of the characteristics such as black balance, gamma value, detail, and masking for a high definition television video signal is adjusted to have a proper value, this proper value becomes improper to a standard television video signal. Conversely, even if each of such characteristics for a standard television video signal is adjusted to have a proper value, this proper value becomes improper to a high definition television video signal.
Still further, in converting the high definition television video signal into a standard television video signal by the television camera signal conversion circuit, the characteristic values of the video signal, such as a black balance value, gamma value and detail value are changed because of the different specifications of the high definition and standard television video signals. Therefore, the characteristic values for the standard television video signal may become improper.
It is therefore a purpose of the present invention to provide a high definition television camera apparatus eliminating the above-described prior art problems.
It is another purpose of the present invention to provide a high definition television camera apparatus capable of independently adjusting each of predetermined characteristic values for a high definition television video signal output from a high definition television image pickup unit (camera head) and for a standard television video signal converted from the high definition television video signal by a television signal conversion circuit.
According to one aspect of the present invention, a high definition television camera apparatus is provided which comprises: a high definition television image pickup apparatus including a high definition television image pickup element for outputting a video signal, and a high definition television video signal correction circuit for correcting the video signal and outputting a corrected video signal having a predetermined characteristic value being suitable for high definition television system which is a high definition television video signal;
a transmission path for transmitting the high definition television video signal supplied from the high definition television image pickup apparatus; and
a camera control apparatus including a television signal conversion circuit for converting the high definition television video signal transmitted via the transmission path into a first standard television video signal and outputting the first standard television video signal, a standard television video signal correction circuit for correcting the first standard television video signal and outputting a corrected video signal having a predetermined characteristic value being suitable for standard television system which is a second standard television video signal, a standard television video signal output terminal coupled with the standard television video signal correction circuit, and a high definition television video signal output terminal coupled with the transmission path.
According to another aspect of the present invention, a high definition television camera apparatus is provided which comprises: a control unit comprising: a high definition television video signal characteristic value adjusting unit for setting a characteristic value for a high definition television video signal; a standard television video signal characteristic value adjusting unit for setting a characteristic value for a standard television video signal; and a controller for outputting a high definition television video signal control signal representative of the set value set by the high definition television video signal characteristic value adjusting unit and a standard television video signal control signal representative of the set value set by the standard television video signal characteristic value adjusting unit; a high definition television image pickup unit for outputting a high definition television video signal, the high definition television image pickup unit comprising: a high definition television image pickup element for picking up an image of an object and outputting a high definition television video signal of the object; and a high definition television video signal correction circuit for correcting a characteristic value for the high definition television video signal supplied from the image pickup element to have the set value represented by the high definition television video signal control signal supplied from the control unit and outputting the high definition television video signal having the set value; and a camera control unit comprising: a high definition television video signal output terminal from which the high definition television video signal itself transmitted via a transmission path from the high definition television image pickup unit is output; a television signal conversion circuit for converting the high definition television video signal supplied from the high definition television image pickup unit into the standard television video signal and outputting the standard television video signal; a standard television video signal correction circuit for correcting a characteristic value for the standard television video signal supplied from the television signal conversion circuit to have the set value represented by the standard television video signal control signal supplied from the control unit and outputting the standard television video signal having the set value; and a standard television video signal output terminal from which the standard television video signal from the standard television video signal correction circuit is output.
In one example of the invention, the high definition television video signal correction circuit corrects a gamma value for the high definition television video signal supplied from the image pickup element to have a proper value for the high definition television video signal and output the high definition television video signal having the first predetermined characteristic value, and the standard television video signal correction circuit corrects a gamma value for the standard television video signal supplied from the television signal conversion circuit to have a proper value for the standard definition television video signal and output the standard television video signal having the second predetermined characteristic value.
In another example of the invention, the high definition television video signal correction circuit further corrects at least one of detail, black balance and masking values for the high definition television video signal supplied from the image pickup element to have a proper value for the high definition television video signal and output the high definition television video signal having the first predetermined characteristic value, and the standard television video signal correction circuit further corrects at least one of detail, black balance and masking values for the standard television video signal supplied from the television signal conversion circuit to have a proper value for the standard definition television video signal and output the standard television video signal having the second predetermined characteristic value.
According to the invention, therefore, the characteristic values such as a gamma value for the high definition television video signal and for the standard television video signal converted from the high definition television video signal can be independently adjusted to have proper values.
In another example of the invention, the control unit further comprises an associative characteristic value adjusting unit for setting in combination characteristic values for both the high precision and standard television video signals, and the controller corrects a set value set by the high definition television signal characteristic value adjusting unit in accordance with a set value set by the associative characteristic value adjusting unit, and outputs the corrected set value as the high precision television video signal control signal, and the controller corrects a set value set by the standard television signal characteristic value adjusting unit in accordance with the set value set by the associative characteristic value adjusting unit, and outputs the corrected set value as the standard television video signal control signal.
Therefore, in the high definition television camera apparatus constructed as above, the characteristic values for both the high definition and standard television video signals can be adjusted in combination to have proper values or desired values.